Method and apparatus for closed loop transmit diversity transmission initial access

ABSTRACT

Uplink precoding in closed loop transmit diversity (CLTD). The methods and apparatus relate to precoder operations during an initial stage using default precoder tap weights, and a second stage wherein precoder weights obtained from a precoder control indicator channel information are used, provided the signal quality of the precoder control indicator channel is sufficiently reliable. The methods and apparatus also relate to procedures for responding to detection of an unreliable pre-coding control information (PCI) carried in a downlink feedback signal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.14/222,667, filed 23 Mar. 2014, which is a Continuation of U.S. patentapplication Ser. No. 13/370,563, filed 10 Feb. 2012, now U.S. Pat. No.8,730,989, which claims priority to U.S. Application No. 61/441,984,filed 11 Feb. 2011; U.S. Application No. 61/481,075, filed 29 Apr. 2011,and U.S. Application No. 61/523,065, filed 12 Aug. 2011, all of whichare incorporated herein by reference.

BACKGROUND

The evolution of the universal mobile telecommunication system (UMTS)wideband code division multiple access (WCDMA) standards on the uplinkhas lagged in the past with respect to downlink transmission. Therequired data transmission on the downlink is usually assumed to belarger for users than the transmission in the uplink direction. It isexpected that the uplink will also evolve and introduce multiple inputmultiple output (MIMO) technologies to reduce the peak data rateimbalance between the two link directions. Moreover, it is desirable tocontinue offering better service for wireless transmit/receive units(WTRUs) at the cell edge.

In order to support a higher data rate via stream multiplexing MIMO, orto support extended coverage via transmit diversity techniques, theuplink of WCDMA may be enhanced with transmit diversity techniques.Potential evolution from single transmit antenna to dual transmitantenna in the UMTS uplink may require the design of a control channelfor carrying the pilot and other control information on the second orthe newly added transmit antenna.

SUMMARY

Methods and apparatus are disclosed for using uplinks in closed looptransmit diversity (CLTD) while operating in a cell forward accesschannel (CELL_FACH) state and in idle mode, as well as forsynchronization procedures with uplink CLTD and feedback qualitymonitoring. The operations are related to one or more radio resourcecontrol (RRC) states, such as a Cell_FACH state, Idle mode, cell pagingchannel (CELL_PCH) state, UTRAN registration area paging channel(URA_PCH) state and a cell dedicated channel (CELL_DCH) state.

The methods and apparatus disclosed include operations during theinitial states and operations for resource access, such as radio linksynchronization, radio link monitoring aspects, operations of a downlinkfeedback signal and uplink pilots during the synchronization stage.

The methods and apparatus disclosed include procedures for the WTRU whenthe pre-coding control information (PCI) carried in a downlink feedbacksignal is no longer reliable.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram of an example wireless transmit/receive unit(WTRU) that may be used within the communications system illustrated inFIG. 1A;

FIG. 1C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 1A;

FIG. 2 shows an example of an enhanced dedicated channel (E-DCH) in acell forward access channel state (CELL_FACH);

FIG. 3 shows an example of E-DCH in CELL_FACH start of transmissiontiming;

FIG. 4 shows an example of an event trigger timeline for common E-DCHoperations;

FIG. 5 shows an example of transmit diversity operation mode;

FIG. 6 shows an example method for transmission mode changes using atrigger;

FIG. 7 shows an example method for transmission mode changes whenreliable control channel reception is declared;

FIG. 8 shows an example method for transmission mode changes uponcollision resolution;

FIG. 9 shows another example method of transmission mode changes uponcollision resolution;

FIG. 10 shows an example method of transmission mode going to CELL_DCHstate, where the WTRU operates in Mode 3;

FIG. 11A shows another example method of transmission mode going toCELL_DCH state, where the WTRU operates in Mode 2 and Mode 3;

FIG. 11B shows another example method of transmission mode going toCELL_DCH state, where the WTRU operates in Mode 1, Mode 2 and Mode 3;

FIG. 12A shows another example method of transmission mode change when apost-verification period is configured, where the WTRU operates in Mode2 and Mode 3;

FIG. 12B shows an example method of transmission mode change when apost-verification period is configured, where the WTRU operates in Mode1, Mode 2 and Mode 3;

FIG. 13 shows another example method of transmission mode change when apost-verification period is configured, where the WTRU operates in Mode3;

FIG. 14 shows an example method of transmission mode change following apower control preamble;

FIG. 15 shows another example method of transmission mode changefollowing a power control preamble;

FIG. 16 shows an example method of transmission mode at the start of apower control preamble;

FIG. 17 shows another example method of transmission mode changefollowing a power control preamble;

FIG. 18 is a block diagram of a WTRU apparatus; and,

FIGS. 19 and 20 are flow charts of some example methods.

DETAILED DESCRIPTION

FIG. 1A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems100 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a radioaccess network (RAN) 104, a core network 106, a public switchedtelephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated that the disclosed embodiments contemplateany number of WTRUs, base stations, networks, and/or network elements.Each of the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d may be configuredto transmit and/or receive wireless signals and may include userequipment (UE), a mobile station, a fixed or mobile subscriber unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,consumer electronics, and the like.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the networks 112. By way of example, the base stations 114 a, 114b may be a base transceiver station (BTS), a Node-B, an eNode-B, a HomeNode-B, a Home eNode-B, a site controller, an access point (AP), awireless router, and the like. While the base stations 114 a, 114 b areeach depicted as a single element, it will be appreciated that the basestations 114 a, 114 b may include any number of interconnected basestations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 116 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed DownlinkPacket Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, Home Node-B,Home eNode-B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 106may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram of an example WTRU 102. As shown in FIG. 1B,the WTRU 102 may include a processor 118, a transceiver 120, one or moretransmit/receive elements 122, a speaker/microphone 124, a keypad 126, adisplay/touchpad 128, non-removable memory 106, removable memory 132, apower source 134, a global positioning system (GPS) chipset 136, andother peripherals 138. It will be appreciated that the WTRU 102 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. It will be appreciatedthat the transmit/receive element 122 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 106 and/or the removable memory 132.The non-removable memory 106 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 1C is a system diagram of the RAN 104 and the core network 106according to an embodiment. As noted above, the RAN 104 may employ aUTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102 cover the air interface 116. The RAN 104 may also be in communicationwith the core network 106. As shown in FIG. 1C, the RAN 104 may includeNode-Bs 140 a, 140 b, 140 c, which may each include one or moretransceivers for communicating with the WTRUs 102 a, 102 b, 102 c overthe air interface 116. The Node-Bs 140 a, 140 b, 140 c may each beassociated with a particular cell (not shown) within the RAN 104. TheRAN 104 may also include RNCs 142 a, 142 b. It will be appreciated thatthe RAN 104 may include any number of Node-Bs and RNCs while remainingconsistent with an embodiment.

As shown in FIG. 1C, the Node-Bs 140 a, 140 b may be in communicationwith the RNC 142 a. Additionally, the Node-B 140 c may be incommunication with the RNC142 b. The Node-Bs 140 a, 140 b, 140 c maycommunicate with the respective RNCs 142 a, 142 b via an Iub interface.The RNCs 142 a, 142 b may be in communication with one another via anIur interface. Each of the RNCs 142 a, 142 b may be configured tocontrol the respective Node-Bs 140 a, 140 b, 140 c to which it isconnected. In addition, each of the RNCs 142 a, 142 b may be configuredto carry out or support other functionality, such as outer loop powercontrol, load control, admission control, packet scheduling, handovercontrol, macrodiversity, security functions, data encryption, and thelike.

The core network 106 shown in FIG. 1C may include a media gateway (MGW)144, a mobile switching center (MSC) 146, a serving GPRS support node(SGSN) 148, and/or a gateway GPRS support node (GGSN) 150. While each ofthe foregoing elements are depicted as part of the core network 106, itwill be appreciated that any one of these elements may be owned and/oroperated by an entity other than the core network operator.

The RNC 142 a in the RAN 104 may be connected to the MSC 146 in the corenetwork 106 via an IuCS interface. The MSC 146 may be connected to theMGW 144. The MSC 146 and the MGW 144 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices.

The RNC 142 a in the RAN 104 may also be connected to the SGSN 148 inthe core network 106 via an IuPS interface. The SGSN 148 may beconnected to the GGSN 150. The SGSN 148 and the GGSN 150 may provide theWTRUs 102 a, 102 b, 102 c with access to packet-switched networks, suchas the Internet 110, to facilitate communications between and the WTRUs102 a, 102 b, 102 c and IP-enabled devices.

As noted above, the core network 106 may also be connected to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

FIG. 2 shows a high level access procedure for enhanced dedicatedchannel (E-DCH) transmission in cell forward access channel (CELL_FACH).In a typical cellular wireless system, idle wireless transmit/receiveunits (WTRUs) may request access to system resources using a randomaccess procedure. In UMTS, the random access channel (RACH) may be usedfor that purpose. The RACH is a part of the wireless protocol and theRACH may be improved to also support E-DCH transmission. At ahigh-level, the E-DCH feature in cell forward access channel (CELL_FACH)mode and idle mode consists of using the E-DCH after access to theresource is granted by the Node-B, via a power ramp-up procedure similarto the legacy procedure.

During closed-loop transmit diversity operations, the Node-B mayindicate, via fast level one (L1) signaling, a set of spatial pre-codedweights the WTRU may use for transmission. By optimizing the choice ofpre-coded weights, the WTRU may require less transmission power for thereceived signal-to-noise ratio (SNR) at the Node-B. This approach mayimprove coverage and reduce inter-cell interference. This may benefitE-DCH in the CELL_FACH state and in idle mode, where soft handover isnot allowed. It may also be used in CELL_DCH mode.

The WTRU may determine uplink transmit diversity mode in CELL_FACHstate, CELL_DCH and idle mode.

In an embodiment, a WTRU may determine to use uplik transmit diversitybased on RRC configuration or reconfiguration messages when enteringCELL_DCH state. In an alternative embodiment, a WTRU may determinewhether or not to use uplink transmit diversity based on networkconfiguration of physical RACH resource partitioning. The WTRUsupporting uplink (UL) CLTD in CELL_FACH and idle mode may determinewhether or not the feature is supported and whether or not to use thefeature. If the feature is supported and is to be used, the WTRU mayreceive configuration and the physical resource partitioning. The WTRUmay access the RACH using the configured subset of physical resourcesknown to both the WTRU and Node-B.

In an embodiment, the WTRU may determine whether or not to use UL CLTDin CELL_FACH, CELL_DCH, and idle mode. To control the support of ULCLTD, the WTRU may be explicitly configured by the network to use ULCLTD (e.g., in CELL_FACH and CELL_DCH state). This may be achieved viaradio resource controller (RRC) configuration. In some embodiments, theWTRU may first indicate in its RRC message that it supports UL CLTDtransmission in CELL_FACH state. The network may respond by configuringthe WTRU for using or not using the feature in the current cell. Thismay include, but is not limited to, CELL UPDATE CONFIRM RRC connectionsetup, radio bearer setup or a RRC reconfiguration message.

In another embodiment, the network may broadcast its capability in thesystem information and the WTRU may determine whether to use it or notin combination with any of the embodiments described herein.Alternatively, the network signals a set of UL CLTD specific resources.Based on the presence of this information element (IE), the WTRU mayimplicitly determine that the cell supports UL CLTD. The WTRU maydetermine whether or not to use UL CLTD in the CELL_FACH state and idlemode based on the support of the feature as broadcast by the cell. Morespecifically, the WTRU may read the system information block (SIB) todetermine if the cell supports UL CLTD in CELL_FACH or idle mode. If thecell supports it and the WTRU supports it, the WTRU may use the featurefor uplink transmission.

In addition to the configuration by the network, the WTRU may optionallyuse one or a combination of criteria to determine whether it can use ULCLTD in CELL_FACH state. The WTRU may have a dedicated E-DCH radionetwork temporary identifier (E-RNTI) configured. Optionally, inaddition to the E-RNTI the WTRU may also have a high speed downlinkshared channel (HS-DSCH) radio network transaction identifier (H-RNTI)and/or a cell radio network temporary identifier (C-RNTI) configured.More specifically, if the WTRU, according to the RRC signaling,determines that the WTRU, the cell and the network support UL CLTD andthe WTRU has an E-RNTI configured, it may use UL CLTD in CELL_FACH. Asan example, upon a cell reselection or radio link failure, the WTRU doesnot use UL CLTD in transmitting the CELL UPDATE to the network.

The WTRU may perform DTCH or DCCH transmission. In some embodiments, theWTRU may not use UL CLTD for common control channel (CCCH) transmission,but may use UL CLTD in CELL_FACH state for dedicated traffic channel(DTCH) and dedicated control channel (DCCH) transmission when itdetermines that the WTRU, cell and the network support the feature.

For performing random access channel (RACH) operation, the WTRU may beconfigured with a number of parameters for performing the power ramp-upprocedure in order to get an acknowledgement (ACK) and permission fortransmission on the UL. The WTRU may be aware of a set of physicalresources that it may use for transmission. These physical resources mayinclude a preamble scrambling code or a set of available signatures anda set of available RACH sub-channels corresponding to E-DCH resourcesfor each Access Service Class (ASC).

In an embodiment, the network may transmit the physical resource for ULCLTD RACH transmission on the SIBs separately from the physicalresources configured for common E-DCH transmission. If the WTRU isconfigured to use UL CLTD, the WTRU may use the physical resources forUL CLTD RACH as transmitted in the separate set of IEs to initiate therandom access procedure. As an example, this may be achieved byintroducing a new IE, a physical random access channel (PRACH) preamblecontrol parameter with enhanced UL CLTD (“PRACH preamble controlparameters enhanced Uplink with UL CLTD”) that contains the PRACHparameters to use for UL CLTD WTRUs. This IE may be included as part ofthe IE common E-DCH system information, or directly in the SIB5/5bis.When the WTRU determines that it may use UL CTLD, it may use this IE todetermine the RACH parameters (e.g., the new IE “PRACH preamble controlparameters enhanced Uplink with UL CLTD”). Alternatively, the WTRU mayuse the same PRACH preamble control parameters regardless of the supportof UL CLTD.

In another embodiment, the network may separate the set of common E-DCHparameters in which UL CLTD may be configured. This may be performed bytransmitting an entire separate set of IEs for WTRUs to use the commonE-DCH within UL CLTD operations. As an example, a new IE “Common E-DCHResource Configuration information list for UL CLTD” may be signaled.The new set of UL CLTD parameters may include a separate set of preamblesignatures and common E-DCH resources. If according to the criteriadescribed above, the WTRU determines that it will be using UL CLTD, itmay choose a preamble signature from the UL CLTD specific list. If apositive acknowledgment is received on the AICH, or if a resource indexis received on the E-AI, the WTRU may determine the E-DCH resource touse from the set of UL CLTD common E-DCH resources (e.g., from IE“Common E-DCH Resource Configuration information list for UL CLTD”).

Alternatively, the preamble signatures used for the preamble ramp-upphase may be a common set of preambles that can be used by all UL CLTDand non-UL CLTD WTRUs, but a separate set of Common E-DCH resources ofUL CLTD may be provided to the WTRU. Alternatively, within the “CommonE-DCH resource information list,” an explicit information element may beadded for each resource that indicates whether the WTRU may use UL CLTDwith this resource. Alternatively, if the resources have the UL CLTDspecific configuration (e.g., precoder control indicator channel orPCICH information or secondary DPCCH information) present, the WTRU mayimplicitly determine that it may use UL CLTD with this resource.

If, upon reception of the acquisition indicator channel (AICH) orextended acquisition indicator (E-AI), the resource index provided tothe WTRU corresponds to a resource that is explicitly or implicitlyindicating the support of UL CLTD, the WTRU determines that it can startusing UL CLTD according to any of the embodiments described herein.Alternatively, a separate IE may be added that indicates explicitly theindex number out of the common E-DCH resource list that may use UL CLTD.

In addition to the common E-DCH resources, additional information may beprovided to the WTRU via the broadcast channel. The additionalinformation may include but is not limited to: precoding controlindicator channel (PCICH) information (which may include achannelization code and a slot format), a secondary DPCCH, which mayinclude a power offset, format, and an initial pre-coding weightrestriction. This information may be signaled as part of the commonE-DCH resource list. More specifically, for every resource in which ULCLTD may be used, this or a subset of this information is signaled.Alternatively, some of these parameters may be provided per resource andsome may be provided as common parameters in the “Common E-DCH info”,for instance.

In an alternative embodiment, for some of these parameters, such as thePCICH information, a pre-defined rule may be defined that allows theWTRU to determine the slot and code with respect to the fractionaldedicated physical channel (F-DPCH). In one solution the PCICH may beadjacent to the F-DPCH field in the same radio slot and may use the samechannelization code.

In another embodiment, the WTRU may explicitly indicate to the networkthat it supports UL CLTD in CELL_FACH state and idle mode. Thiscapability may be reported to the network by the WTRU in the RRCconnection request or in the RRC Connection Setup Complete. To furtherallow the cell to determine whether the WTRU supports UL CLTD as itperforms cell reselection, the WTRU may further report the capabilitywith a cell update message. Upon every cell reselection, the WTRU maytransmit this capability to the network. This may always be performed,or may only be performed upon determining that the network supports thecapability.

In another embodiment one common capability may be that the WTRUincludes both CELL_FACH and CELL_DCH. More specifically, if the WTRUsupports UL CLTD, it may support all states. This may be reported to thenetwork in a manner similar to the UL CLTD in CELL_FACH approach.

In another embodiment, the network may implicitly determine that theWTRU supports UL CLTD in CELL_FACH and/or CELL_DCH based on the PRACHresources that it used to perform UL access. This may allow the WTRU tonot include the capability in every CELL Update.

The WTRU may report this capability in a medium access control packetdata unit (MAC PDU), using a special header field in the MAC-i header toindicate the presence, or optionally, as part of collision resolution.These embodiments may be used individually or in any combination. Forexample, the UL CLTD capability may be reported as part of the RRCestablishment procedure, and further implicitly determined by thenetwork (e.g., while operating in CELL_FACH state), based on theresources used by the WTRU.

In another embodiment, the WTRU may receive an explicit message from theNode-B to indicate operation in UL CLTD mode. In an embodiment, when theWTRU and the cell support UL CLTD operations in CELL_FACH, the WTRUinitiates UL CLTD operations after receiving the E-DCH absolute grantchannel (E-AGCH) with its E-RNTI, after the collision resolution phaseis completed successfully. This approach allows the radio link to besynchronized before sending weight indications to the WTRU. Thisapproach may also prevent creating excessive interference when acollision occurs and more than one WTRU has started transmission.

In another embodiment, the WTRU receives an explicit indication to startusing UL CLTD mode after collision resolution has completedsuccessfully. In one embodiment, this indication may be carried, forexample, using the E-AGCH upon collision resolution.

In another embodiment, the WTRU may be configured with two (2) E-RNTIs.One E-RNTI may be used by the network in collision resolution toindicate that the WTRU may use UL CLTD operations. The other E-RNTIindicates regular, no transmit diversity, operations.

In another embodiment, a special value, or a set of values, of anabsolute grant in the E-AGCH is reserved to indicate that the WTRU mayuse UL CLTD operations. Upon reception of this grant value on the E-AGCHfor the contention resolution, the WTRU may keep using the default grantand initiate UL CLTD operations.

In another embodiment, the Node-B may explicitly configure the WTRU tostart using UL CLTD via a high speed shared control channel (HS-SCCH)order. A new order to activate/deactivate UL CLTD may be provided. Thisorder may be specific to the CELL_FACH state or may be an order that isdefined and may be used in all states. The order may be used aftercollision resolution is completed and the network is aware of the WTRUidentity that is using the resource, it may able to explicitlystart/stop the UL CLTD operation.

In another embodiment, the network may explicitly configure the WTRUusing a MAC PDU, by adding a MAC control element in the downlink andindicating the presence of this control element via a special MAC-ehsheader.

The WTRU may apply transmit diversity as will now be discussed.

In an embodiment, an initial weight selection is defined. The WTRU maybe configured by the network to use a specific pre-coded weight duringthe initialization period. This weight may be configured as a commonvalue for all common E-DCH resources. Each E-DCH resource may beconfigured with a specific weight value. Alternatively, the pre-codedweight may be signaled in the HS-SCCH order or in the MAC PDU used toinitiate UL CLTD.

In another embodiment, the initial weight may be fixed by specifications(i.e., predetermined). The weight may be a special pre-coded weight, forinstance the weight vector value [1 0] or [0 1] which may correspond totransmitting all the data and control information on a single antennaand at least one control channel carrying pilot may be transmitted oneach antenna for channel estimation purposes. The predetermined weightsmay be a predetermined precoder codebook entry.

FIG. 3 shows a transmission time interval (TTI) for a closed loopoperation, including a PRACH preamble ramp-up. In common E-DCHoperations, the WTRU may start uplink transmission at a fixed timeoffset after receiving the ACK on the AICH. The WTRU may transmit uplinkDPCCH during a configurable number of TTIs (i.e., a minimum 2 TTIs for 2ms TTI plus an additional E-DCH transmission back-off configured by thenetwork) and may then transmits E-DCH.

The PRACH preamble ramp-up is designed to allow the WTRU to reach therequired power to establish initial radio connection with the Node-B.When the Node-B detects a preamble, it may respond with an ACK on AICHindicating that further transmission is permitted

A DPCCH-only or E-DCH transmission back off period may be used forstabilizing a power control loop in both UL and DL communications.Post-verification may be used for common E-DCH. In addition, there maybe several transmission modes.

In a transmission mode, Mode 1, the WTRU may not apply any transmitdiversity and may not transmit any information on its second antenna.For convenience, this mode may be referred to as “no transmit diversity”or “No-TD mode”. It is possible that some WTRUs implement transmitinformation on more than one antenna even in this mode. However, it isassumed that the Node-B and network are unaware of it. This mode may beused as a “default” transmission mode before the WTRU changes to atransmit diversity mode.

In a transmission mode, labeled Mode 2, may be used as a default mode,such as when entering CELL_DCH mode, where the WTRU may apply transmitdiversity by pre-coding, with a first pre-coding weight, one or more ofthe DPCCH, the E-DCH and high-speed dedicated physical control(HS-DPCCH) channels. The WTRU may also transmit the secondary pilotcontrol channel (or S-DPCCH) on the second pre-coded weight. In thistransmission mode, the WTRU may monitor the downlink pre-coding controlinformation (PCI) but does not apply the weights that are signaled. Forconvenience, this mode will be referred to as “open-loop transmitdiversity” or “OLTD” mode. In this transmission mode, the WTRU may alsobe operating in open loop transmit diversity and adjusts its weightsbased on implicit feedback from the Node-B (e.g., based on TPC commands,ACK/NACK, etc.). Alternatively in this transmission mode, the WTRU maybe operating with space-time transmit diversity (STTD) for example.

In a transmission mode, Mode 3, the WTRU operates in full closed looptransmit diversity mode. The WTRU applies transmit diversity bypre-coding with a first pre-coding weight the DPCCH and optionally, theE-DCH and HS-DPCCH channels. The WTRU may also transmit the secondarypilot control channel (or S-DPCCH) on the second pre-coded weight. Inthis transmission mode, the WTRU monitors the downlink PCI and appliesthe weights that are signaled just as in a regular closed loop operationin CELL_DCH. For convenience, this mode will be referred to as“closed-loop transmit diversity” or “CLTD” mode. Also in this mode, fora short period of time at the initialization, the WTRU may use apre-defined precoding vector until it receives the first PCI from theNode-B. The Node-B may start transmitting the PCI information before itreceives the DPCCH and S-DPCCH (i.e., with incomplete channel estimate).In such case, the Node-B may indicate a precoding weight that does notdepend on channel estimates (with some performance degradation).

In addition, a number of event triggers may be used. Using an eventtrigger, Trigger 1, the WTRU starts transmitting the UL DPCCH afterreceiving the ACK on AICH (t_(a-m) after the beginning of the AICH slotcarrying the ACK). Using an event trigger, Trigger 2, the WTRU startstransmitting E-DCH on the uplink after the E-DCH transmission backoffperiod has elapsed. Using an event trigger, Trigger 3, post-verificationmay have succeeded. This occurs 40 ms after the WTRU has started uplinktransmission. Using an event trigger, Trigger 4, the WTRU has monitoredthe quality of the PCI channel and has declared it to be sufficientlyreliable. Using an event trigger, Trigger 5, the WTRU has received theE-AGCH with its E-RNTI and the collision resolution is successful. Usingan event trigger, Trigger 6, the WTRU receives a special indication bythe network to initiates transmit diversity operations (e.g., high-speedshared control channel (HS-SCCH) order for activation of UL CLTD). Uponan event trigger, Trigger 7, the WTRU may start transmitting PRACHpreambles during the RACH power ramp-up procedure. Another trigger,Trigger 8, indicates that a certain amount of time (e.g., expressed innumber of slots, subframes or frames) has elapsed since the WTRU hasstarted transmission or another known time reference. In one example,such trigger could be linked to the second phase of the synchronizationprocedure (i.e. 160 ms after the downlink physical channel is consideredestablished). In another example, this trigger could be linked to thestarting time of the uplink E-DCH transmission.

FIG. 4 illustrates an example timeline with an indication as to wherethe triggers may occur. The order of the triggers shown in FIG. 4 is fordemonstrative purpose only. It should be understood, that even thoughTrigger 6 is shown before Trigger 5 in FIG. 4, it may also occur afterTrigger 5. Also, for convenience, only the channels PRACH, DPCCH andE-DCH are shown, but other channels may be similarly controlledaccording to transmission modes described herein.

In a most general form of this method, the WTRU may be configured to usetransmission diversity in increasing mode order (starting from Mode 1 upto Mode 3), changing mode based on pre-configured event triggers. WTRUmay be configured to start a transmission mode larger than Mode 1, andtriggers may be used in any order or combination. In one embodiment, theWTRU may begin in Mode 2 when in CELL_DCH mode, and move to Mode 3 usinga trigger, such as trigger 4, based on the quality of the quality of thePCI channel. In further embodiments, the WTRU may be configured to applya change of transmission mode a fixed period of time after an eventtrigger.

FIG. 5 shows an embodiment where the WTRU may be configured to usetransmission diversity Mode 2 open-loop transmit diversity (OLTD) uponstarting the UL transmission using Trigger 1. In an embodiment, thepre-configured pre-coded weight consists of the [1 0] weight for themain, or primary beam, carrying the DPCCH, E-DCH and optionally theHS-DPCCH, and [0 1] for the secondary beam carrying the S-DPCCH. TheWTRU may then move to the transmission diversity Mode 3 CLTD a fixedtime after transmission has started. This fixed time period may be longenough to allow the network to perform reliable channel estimation andtransmit the PCI on the downlink. For example, the WTRU may beconfigured to start CLTD operations, and apply weights as signaled onthe PCI, five slots after the beginning of the UL OLTD transmission(e.g., three slots for UL channel estimation and two more slots for PCIdelay transmission).

In an embodiment for closed loop operation with common E-DCH, the WTRUstarts uplink transmission using a No-TD mode during the DPCCH onlyphase. At the end of the E-DCH transmission back-off using Trigger 2,the WTRU starts using OLTD mode with a pre-configured pre-coded weight.In an embodiment, the pre-configured pre-coded weight consists of the [10] weight for the main, or primary beam, carrying the DPCCH, E-DCH andoptionally, the HS-DPCCH, and [0 1] for the secondary beam carrying theS-DPCCH. Optionally, to account for PCI estimation and transmissiondelays, the WTRU applies the signal weights a fixed period of time afterTrigger 2, which is a fixed period of time (e.g., 2 slots) after theE-DCH transmission backoff period is completed. The WTRU may then moveto transmission Mode 3 upon another event trigger. For example, afterthe post-verification period is considered successful it may use Trigger3, when the WTRU determines that the PCI reception quality is goodenough it may use Trigger 4, after successful collision resolution itmay use Trigger 6, or after reception of an explicit signal by theNode-B to initial CLTD it may use Trigger 7. FIG. 6 shows an examplecase where Trigger 3 is used to move to transmission Mode 3.

In another embodiment for closed loop operations with common E-DCH, theWTRU may use transmission Mode 1 until reliable reception of thedownlink control channels is confirmed and then may move to transmissionMode 2, for a short transition, and Mode 3. For example, the WTRU maytransmit using Mode 1 until post-verification is successful usingTrigger 3, and then start transmitting using transmit diversity. TheWTRU may use Mode 2 transmission operations for a fixed period of timeafter which the WTRU may initiate Mode 3 transmission operations. Thisperiod of time after Trigger 3 is used may allow for proper channelestimation at the Node-B and the processing/transmission delay for thePCI indication. This embodiment is illustrated in FIG. 7. Thisembodiment may also be used during synchronization in CELL_DCH.

In an alternative embodiment, the WTRU may also use the collisionresolution trigger, Trigger 5, to change the transmission mode. Thisembodiment is illustrated in FIGS. 8 and 9.

The WTRU may further be configured to change the transmission followingTrigger combinations. In one embodiment, the WTRU is configured tochange the transmission mode (e.g. from Mode 2 to Mode 3) aftercollision resolution (Trigger 5) and only if the WTRU has determinedthat the quality of the PCI channel is sufficiently reliable (Trigger4).

Three different transmission modes have been defined above: Mode 1, Mode2, and Mode 3. In transmission Model, the WTRU does not apply transmitdiversity, in Mode 2, the WTRU applies transmit diversity but does notchange the weights based on the Node-B PCI signalling, and in Mode 3,the WTRU operates in normal UL CLTD operations, applying the weighs assignalled by the Node-B. various embodiments use only a subset of thesemodes, such as modes 1 and 3, modes 2 and 3, etc.

Upon changes of transmission mode, the WTRU may have to adjust itstransmission power to ensure that the signal is received at the Node-Bwith the appropriate power, without causing too much undue interferencein the other cells.

In one method to ensure that appropriate transmit power is used, theWTRU applies a power backoff when changing transmission mode. The WTRUmay receive the power backoff configuration via RRC signalling or theamount of power backoff may be pre-configured in the specifications. TheWTRU may be configured to apply a different power backoff for eachpossible transmission mode transition. As a special case, sometransition may be configured with a power backoff of 0 dB (i.e. nobackoff). An example power backoff transition table is shown in Table 1,where most of the entries are configured with a 0 dB backoff (i.e. nobackoff).

TABLE 1 Example power backoff transition table Power backoff (in dB)Transition to: Mode 1 Mode 2 Mode 3 Transition from: Mode 1 0 −1 −3 Mode2 0 0 −2 Mode 3 0 0 0

In one specific example of this method, a power backoff is applied onlywhen the WTRU transitions to transmission Mode 3 (from Mode 1 or Mode2). Furthermore, in this case, a single power backoff value may beconfigured, regardless of the origin transmission Mode.

The WTRU may apply the power backoff on the DPCCH directly such that allother physical channels are affected accordingly. For example, theinitial uplink DPCCH transmit power after mode transition can becomputed (in dB) as:

Uplink DPCCH transmit power=PDPCCH+Power backoff

where PDPCCH is the uplink DPCCH transmit power of the last DPCCH slotbefore switching of the transmission mode.

The power backoff is applied once and it is assumed that the inner looppower control will further adjust the WTRU transmit power to theappropriate value.

Several embodiments for performing a synchronization procedure will nowbe described, which relate to the WTRU having UL CLTD capability, wherea second DPCCH or S-DPCCH is also transmitted together with the firstDPCCH, or simply DPCCH during the normal operation.

A number of event triggers are defined for this embodiment fortransmission mode to going to CELL_DCH, including the following. Upon anevent trigger, Trigger 9, the WTRU may start the transmission of thepower control preamble (similar to Trigger 1 described above). Inresponse to an event trigger, Trigger 10, the WTRU may end transmissionof the power control preamble and starts transmission of the E-DCH(similar to Trigger 2 above) or DCH. An event trigger, Trigger 11,indicates that the WTRU has monitored the quality of the F-DPCH channeland the WTRU higher layers consider the downlink physical channelestablished. In response to a Trigger 12, the WTRU may start ULtransmission in CELL_DCH when post-verification is configured, assumingthe downlink physical channel is established (similar to Trigger 11).One or more of these trigger events may be used depending on theconfiguration.

The power control preamble consists of the WTRU transmitting only DPCCHfor a configured number of frames before starting transmission of dataor other control channels.

Depending on whether the WTRU is configured to use post verificationand/or a power control preamble during synchronization procedures,several configuration scenarios and different uplink transmissionschemes may be used, as described below. It should be understood thatalthough different uplink transmission schemes and solutions arepresented in the following under the context of each scenario, thesesolutions may also apply to the other scenarios. In the following, theE-DCH is used for convenience in the description of the operations. Itshould be understood that the methods are not limited to E-DCHoperations, for instance the DCH may also be equivalently used or acombination of the E-DCH (2 ms TTI or 10 ms TTI) and the DCH.

In an embodiment, neither a post verification nor power control preamblemay be configured. Power control preamble may be considered notconfigured when it is configured to value 0 (i.e., PC preamble isconfigured to 0 frames). The uplink transmission may begin after DLsynchronization has been achieved, or more specifically when the higherlayers consider the downlink channel established (Trigger 11).Therefore, the WTRU may operate in normal CLTD fashion (e.g., Mode 3).As the initial precoding vector (before the first PCI is received fromthe PCI channel (PCICH)), the WTRU may use a precoding vector signaledvia a higher layer.

FIG. 10 shows an example transmission mode going to CELL_DCH. As shown,the Node-B may signal a PCI on the PCICH before it has received pilotsignals, thereby choosing arbitrary weights.

FIG. 11A shows another example transmission mode going to CELL_DCHrelated to the PCI. The WTRU may start transmission in Mode 2 with apre-defined pre-coding weight when the WTRU declares that the downlinkphysical channels are established. Once the WTRU receives a specialindication by the network (e.g., Trigger 6), or when the WTRU determinesthat the downlink channel carrying the PCI is sufficiently reliable(e.g., Trigger 4), or after a specific timer has expired (e.g, Trigger8), the WTRU may start transmitting in Mode 3 with full CLTD support.The WTRU may be configured in such cases to transmit the S-DPCCH onlyfor a specific amount of time before the UE transitions to transmissionMode 3.

FIG. 11B shows another example transmission mode going to CELL_DCH. TheWTRU may transmit in Mode 1 (no transmit diversity) until a relevantTrigger is detected (i.e. Trigger 4, 6 or 8 for instance). Then the WTRUmay transmit the S-DPCCH for a specific period of time (essentiallyoperating in transmission Mode 2) before fully operating in Mode 3.

In another embodiment, the WTRU is configured to use post-verification,and the WTRU may start transmission immediately when the physicaldedicated channel establishment is initiated by the WTRU. In thisscenario, before the post verification period elapses, the WTRU assumesthat the downlink physical channel is established.

Since the quality of the downlink channel is not verified beforeinitiating uplink transmission, there could be negative impact on theuplink performance due to potentially low feedback channel reliabilityif the normal CLTD mode were applied before the physical downlinkchannel is established.

In one approach, transmit diversity is not applied before the downlinkphysical channel is established and post-verification has been confirmed(or has not failed after 40 ms of the period of the first phase of thedownlink synchronization) (i.e., Trigger 3). In this approach, theS-DPCCH may be transmitted before that time such that the Node-B candetermine the precoding weight vector to be used after post verificationis confirmed.

FIG. 12A shows an example for a transmission mode change relative to apost-verification period. The WTRU may transmit both DPCCH and S-DPCCHwith a pre-defined precoding vector (Mode 2) until post-verification isconfirmed (Trigger 3), after which the WTRU transmits in normal CLTDmode (Mode 3). The pre-defined precoding vector may be, for example, aspecial vector that may be used only during post-verification period, oralternatively a precoding vector that is part of the normal precodercodebook. In one example, the precoder is selected such that the DPCCHand other uplink physical channels are transmitted on the first antennaand the S-DPCCH on the second antenna (e.g., [1 0] and [0 1] vectors).For more transmit power efficiency, the S-DPCCH may be gated and itstransmit power may be scaled down with respect to DPCCH transmit power.

FIG. 12B shows an alternative method where the S-DPCCH is onlytransmitted shortly or a fixed amount of time before Trigger 3 to allowNode-B estimation of the channel.

FIG. 13 shows an example for a transmission mode change occurring duringthe post verification period. The WTRU may transmit using a normal CLTDmode during the post verification period. Therefore, when the downlinkchannel quality may be superior, the UL transmission delay may beminimized. The WTRU may use pre-configured precoding weights forinitialization or alternatively may monitor the channel carrying the PCIand use those weights as signaled by the Node-B, in which case theNode-B may have to signal PCI weights without having received WTRUpilots yet, thereby signalling arbitrary weights for a few slots orsubframe.

In another embodiment, during the post verification period, the WTRUtransmits using Mode 1.

For the above cases related to the post verification period, if thepost-verification fails, the WTRU may stop uplink transmission andresumes transmission only when the higher layers determine that thedownlink physical channel is established. The WTRU may then revert backto the cases described above in which neither post verification norpower control preamble is configured.

In another embodiment, WTRU is configured to use a power controlpreamble. WTRU may not transmit on the uplink physical channel until apredefined amount of uplink DPCCH power control preamble radio frameshave been transmitted.

FIG. 14 shows an example transmission mode change based on the powercontrol preamble. The WTRU may transmit DPCCH and S-DPCCH during thepower control preamble, each on a different antenna or using apre-defined precoding weight. The WTRU may start using the transmittedweights on the PCI channel after it has completed transmission of thepower control preamble. The signals should be fairly reliable as powercontrol should be stabilized in both directions.

FIG. 15 shows another example transmission mode change based on thepower control preamble. The WTRU may transmit non-precoded DPCCH on oneantenna during the power control preamble. Transmission in Mode 3 maystart once transmission of the power control preamble has completed.Optionally, the WTRU may be configured to start transmission of theS-DPCCH shortly before the end of the power-control preamble to allowthe Node-B to perform channel estimation. In such cases, the WTRU mayuse a pre-defined precoder for the DPCCH and S-DPCCH (e.g., in oneexample the DPCCH and S-DPCCH may be transmitted on the main andsecondary antenna, respectively).

FIG. 16 shows an example of the WTRU transmitting both DPCCH andS-DPCCH, both of which are pre-coded using the PCI signaled fromdownlink from the start of the power control preamble. In this methodthe Node-B signals arbitrary weights (or weights not necessarily basedon channel estimates) for a few slots or subframes before it has asufficiently reliable channel estimate to signal appropriate weights.

FIG. 17 shows an example of the WTRU operating in transmission Mode 2transmitting both the DPCCH and the S-DPCCH during the PC preamble phasefrom the start of uplink transmission (Trigger 9) using a preconfiguredprecoding weight. After a specific amount of time after starting uplinktransmission on the E-DCH (or DCH) (Trigger 10), the WTRU may startoperating in UL CLTD (transmission Mode 3). The time duration betweenthe end of the PC preamble phase and the start of UL CLTD operations maybe pre-defined in the specifications, or configured via higher layersignaling (e.g. RRC signaling) from the network. The WTRU may receivethis configuration within a RRC configuration message.

There may be several WTRU behaviors when a downlink PCI of inferiorquality is detected. If the PCI transmitted from the downlink is notreliable, it may be detrimental to the uplink power control loop inwhich the uplink transmitted power could be mistakenly increased. Thiswould cause not only excessive power consumption at the WTRU, but alsocreate an unnecessary noise rise at the neighboring cells. The followingmechanisms for the WTRU enable detection of poor PCI received quality.The following rules govern the related WTRU behavior.

The WTRU may detect and monitor the quality of PCI according to thefollowing. In one approach, the WTRU may use an approach similar to theconventional mechanism for determining the quality of the F-DPCH. TheWTRU may measure the quality of the PCH and if the quality is below apredefined threshold for a certain period of time, the WTRU may declarethe PCI to be unreliable. Likewise, when the quality of the PCI is abovea second threshold for another predefined period of time, the WTRU maydeclare the PCI to be reliable. The threshold values may be pre-definedand may be fixed in the specifications or configured. The two qualitythresholds may be different from each other.

When the PCI quality becomes poor or better, the WTRU may change how theuplink precoding weights are used. The following methods may be used inany order or combination in such a situation.

In one embodiment shown in FIG. 19, the method 1900 may includegenerating a precoded dual-stream cdma signal at a WTRU usingpredetermined precoder weights as depicted in block 1902. Thedual-stream CDMA signal may include at least a control channel in afirst stream and a pilot signal channel (also a type of control signal)in a second stream, or a control channel and a data channel in a firststream and a pilot-control signal channel in a second stream. Othercombinations are also possible.

The predetermined weights are determined by the WTRU in that a defaultset of weights is prearranged for use. The predetermined precoderweights comprise a first weight and a second weight that are applied tothe first stream and a third weight and a fourth weight that are appliedto the second stream. The predetermined weights may be any set ofweights, and may be a set that is identical to a set contained in theprecoder codebook that is used in the closed loop mode of operation. Thepredetermined set is thus a set that is selected without reference to,or in response to the measured channel characteristics. The dual streammay be generated using the WTRU 1800 shown in FIG. 18. The precodeddual-stream cdma signal is then transmitted by the WTRU. The precoderfeedback information is then received on a precoder control informationchannel (e.g., PCICH) at the WTRU as depicted in block 1904. Theresource information corresponding to the precoder control informationchannel may be sent to the WTRU, e.g., in a configuration message suchas an RRC configuration or RRC reconfiguration message. The resourceinformation may include a channelization code and a slot format.

The PCICH may use a channel format similar to that used for theFractional-Dedicated-Physical-CHannel (F-DPCH). The WTRU may thendetermine a quality indicator of the precoder control informationchannel as depicted in block 1906. The quality indicator, or reliabilityindicator, may be a measure of the overall reliability of thedecoded/demodulated PCI information. The PCI information may be conveyedusing one or more symbols, and the quality of those symbols, and/or thelikelihood of them having been received error-free, may be determinedusing any number of techniques. For example, a signal-to-noise ratio maybe calculated, or receive signal strength may be determined. Thesevalues are often used to determine, or used as a proxy for, aprobability of error. Any other well-known technique, such as that usedas a basis to determine signal quality measurements of the F-DPCH, maybe used as a basis to generate the quality indicator. The measurementsmay be of the most recent PIC symbols, or of the most recent completeset of PCI symbols, or some average of received PCI symbols,

At block 1908, the WTRU generates and transmits a precoded dual-streamcdma signal at a WTRU using feedback precoder weights determined basedon the precoder feedback information when the quality indicator is abovea threshold. That is, if the PCI information carrier on the PCICH isdeemed reliable, and reasonably error free, by virtue of the qualityindicator being above a threshold, then the precoder is configured touse the weights corresponding to the signaled PCI information. Theprecoder information may be a plurality of bits that are used toidentify a corresponding set of weights in the precoder codebook at theWTRU. Again, the feedback precoder weights comprise a first weight and asecond weight that are applied to the first stream and a third weightand a fourth weight that are applied to the second stream. The methodmay further include using previously received feedback information todetermine precoder weights when the quality indicator drops back belowthe threshold. The precoder will only use newly received PCI informationif that information is deemed to be reliable.

In a further embodiment shown in FIG. 20, a method 2000 comprisesgenerating a transmit diversity signal using default precoder weights ata WTRU as shown in block 2002. The quality measurement of the precoderfeedback channel PCICH, which carries the precoder feedback informationis then determined at block 2004. At decision block 2006, the qualityindicator is compared to a threshold, and in response, either the WTRUcontinues to generate the transmit diversity signal using the defaultprecoder weights if the quality measurement is below the qualitythreshold as shown in block 2008, or the WTRU generates the transmitdiversity signal using precoder weights based on the precoder feedbackinformation if the quality measurement is above the quality threshold.

As shown in FIG. 18, block portions of a WRTU are depicted in aconfiguration to implement methods described herein, including method1900 and 2000, described above. FIG. 18 provides additional details ofthe WTRU depicted in FIG. 1B. The WTRU apparatus of FIG. 18 includes adual-stream cdma signal generator 1802 that generates streams 1804 and1806, a precoder 1803, a precoding weight selector 1808, and a precoderfeedback processor 1810. The dual stream cdma signal generator 1802 isconfigured to carry at least a control channel in a first stream and atleast a pilot signal channel in a second stream. Further, additionalchannels may be present in one or both streams, depending on how theWTRU is configured, as described herein.

The precoder 1803 is configured to apply precoding weights W1, W2, W3,and W4, which are provided by the precoding weight selector 1808. Theprecoder feedback processor 1810 is configured to determine precoderfeedback information (PCI) received on a precoder control informationchannel (PCICH). The precoder feedback processor 1810 is also configuredto determine a quality indicator of the precoder feedback channel. Thismay be done using the calculations described above. Further, theprecoder feedback processor 1810 is configured to provide a first set ofpredetermined precoder weights W1-W4 to the precoder 1803 of the dualstream cdma signal generator 1802 during one stage, or mode ofoperation, as described above. That is, this stage may be an initialstage of CELL_DCH state, or during an initial or intermediate stage ofCELL_FACH state, etc. The precoder feedback processor 1810 is alsoconfigured to provide a second set of precoder weights W1-W4 determinedbased on the precoder feedback information when the quality indicator isabove a threshold.

The precoder feedback processor 1810 of the WTRU may be configured todetermine the predetermined weights without reference to channelcharacteristics. That is, the predetermined weights may be a pre-agreedupon set of weights, such as a default set of weights. The WTRU may beconfigured to receive a parameter indicating the resource information ofthe precoder feedback channel PCICH. The precoder feedback processor1810 may be configured to determine the quality indicator using ameasurement method that is based on the measurement method used fordetermining quality of a F-DPCH Fractional-Dedicated-Physical-CHannel(F-DPCH).

The precoder feedback processor 1810 may also be further configured insome embodiments to use previously received feedback information todetermine precoder weights when the quality indicator drops back belowthe threshold.

In an embodiment related to timer handling, the WTRU may continue to usethe pre-coding weight vector indicated by the most recent PCI whosequality is reliable for a predefined period of time. The predefinedperiod may be implemented via timer which may be trigged by a detectionof an unreliable PCI reception and reset by a declaration of a reliablePCI reception. The value of the timer may be signaled via RRC signalingfrom a Node-B.

The value of timer may be signaled via RRC signaling from the networkNode-B. While the value of timer may be decided by the RNC, it may alsobe relevant for each Node-B to determine the appropriate value based onits own power setting strategy. In one approach, the Node-B indicates toits controlling RNC the value of the timer that it prefers. This can besignalled at initialization, periodically and/or whenever this valuechanges.

In another approach, the RNC probes the Node-B for the timer valuebefore configuring the UE. A similar timer could also be used when thequality of the PCI returns to acceptable levels.

The WTRU may respond to detection of inferior PCI quality according toany one or more of the following actions that may be performed in anyorder or combination.

The WTRU may hold the precoding weights.

The WTRU may continue to use the precoding weight vector indicated bythe most recent PCI whose quality is sufficient reliable until a new orupdated PCI which is deemed reliable by the WTRU, at which point theWTRU resumes normal CLTD operations.

The WTRU may Stop UL CLTD mode by autonomously disabling transmitdiversity, reverting back to the conventional non-diversity mode asdefined in existing standard. In this non-transmit diversity mode, theDPCCH and other existing uplink channels are not precoded and transmiton one antenna and S-DPCCH is not transmitted.

The WTRU may transmit using a pre-defined precoding weight. In oneexample, a special precoding weight may be used where where DPCCH andother existing uplink channels are transmitted on one antenna andS-DPCCH is transmitted on the other antenna. The S-DPCCH continues to betransmitted.

The WTRU may autonomously change to one of the allowed transmitdiversity configurations (UL CLTD active or not (in which case primaryor secondary antenna used), S-DPCCH transmitted or not). For instance,the WTRU may be pre-configured to transmit with the secondary antennaonly without S-DPCCH transmitted.

The WTRU may transmit a message to the Node-B indicating the loss ofquality on the PCI channel. While it has been proposed to carry thisinformation on the S-DPCCH, it may be more relevant to carry thisinformation elsewhere such as in a new field of the DPCCH, or using aMAC-level message. The WTRU may use a new MAC-header where a 1-bit fieldwould indicate whether or not the PCI is received with sufficientquality by the WTRU. When the WTRU detects that the quality of the PCIis inferior, the WTRU sets the bit to a specific value. The WTRU maythen reset the bit when the PCI quality is sufficiently good. Such afield may be inserted in the MAC-e/MAC-is/i header. This solution isapplicable to operations with E-DCH configured. Otherwise, when no E-DCHis configured, a new header may be inserted in the MAC-d header, and theNode-B could get this information by reading the content of the MAC-dheader.

Alternatively, the WTRU may also be configured to use a different pilotsequence on the S-DPCCH when the F-PCICH quality falls below athreshold. In one approach, the alternate pilot sequence is derived fromthe original pilot sequence via a (simple) mathematical operation. Forexample, the alternate pilot sequence may be obtained by inverting thebits of the original pilot sequence. In another approach, the WTRU mayuse a pre-determined alternate pilot sequence fixed in thespecifications.

The WTRU may transmit an RRC message to the RNC indicating the loss ofPCI signal quality. The RRC message may contain additional informationpotentially to assist the RNC in making an appropriate decision withrespect to UL CLTD operations. Additional information may include, forexample, downlink signal quality (e.g. downlink Ec/No, downlinkpathloss, RSCP, etc.) from serving Node-B and other Node-Bs/cells in theactive set, or (in addition) in the vicinity. In a first example, theWTRU may determine autonomously which cells are in the vicinity, forinstance based on quality measurement and some configured threshold. Inanother example, the WTRU may be configured to transmit qualityinformation of only a subset of the cells (e.g. the WTRU may beconfigured to report transmission quality of a maximum of 3 cells). TheWTRU may then choose to transmit the information of only the best cells.The additional information may also include estimated WTRU velocity(e.g., based on Doppler measurements or other) and/or a timestamp toindicate at which time the loss of PCI quality happened.

Note that this approach is particularly useful in the case where thereis no HSDPA configured and the WTRU is not monitoring the HS-SCCH. Insuch cases, the Node-B has no means to reconfigure the WTRU and theinformation would need to be relayed to the Node-B. In oneimplementation of this approach, the WTRU is configured to only transmitthis RRC message in case there is no HSDPA configured, or that the WTRUis not monitoring the HS-SCCH for UL CLTDactivation/deactivation/configuration change orders.

The WTRU may declare radio link failure and execute the conventionalactions related to RLF, potentially adding a new cause (e.g. “PCIfailure”) to the cell update cause IE in the CELL UPDATE RRC message.

The WTRU may respond to detection of a change from inferior PCI qualityto an acceptable PCI quality (based on appropriately configuredthresholds, for instance), in any one or more of following examples, inany order or combination.

The WTRU may resume UL CLTD operations, applying the indicated PCIweights on its uplink transmission.

The WTRU may transmit a message to the Node-B indicating that the PCIquality is back to acceptable levels. Similar methods as what isproposed above to indicate loss of quality to Node-B could be used aswell. Similarly, the WTRU may transmit an RRC message to indicate to thenetwork that quality of PCI has come back to an acceptable level.Additional measurements or information such as what is described abovemay also be included.

The WTRU may autonomously resume transmission of the S-DPCCH (forexample in the case where its transmission had been interrupted).

The WTRU may autonomously change to one of the allowed pre-definedtransmit diversity configurations, such as UL CLTD active or not (inwhich case primary or secondary antenna used), or S-DPCCH transmitted ornot. For instance, the WTRU may be pre-configured to transmit with theprimary antenna only with S-DPCCH transmitted.

The following is an example of combinations of the methods describedabove to illustrate one possible solution. In this example, the WTRUdetects inferior PCI quality. Then the WTRU holds the PCI weights andstarts a timer. When the timer expires, the WTRU autonomously stopstransmitting the S-DPCCH and starts operating without UL CLTD (i.e., theWTRU transmits over the primary antenna only). When the WTRU detectsthat the PCI quality has resumed to acceptable levels, the WTRU starts atimer and initiate transmission of the S-DPCCH. When the timer expires,the WTRU starts operating in normal UL CLTD operations, applying theweights as indicated by the Node-B on the DL.

The following examples relate to network actions in response to PCIquality. In a first example, the Node-B detects if the WTRU receives thePCI with inferior quality by monitoring the changes in channel with thePCI it indicates on the downlink. This approach may be used incombination to assisted techniques where the WTRU also indicates to theNode-B the status of the PCI link quality.

When the Node-B detects that the WTRU receives the PCI with inferiorquality it may indicate it to the RNC. This may be achieved for examplevia a new Iub message. This message may contain a status flag indicatingthat the WTRU receives the PCI with inferior quality (or the messageitself may carry this information) with optional additional information.Such additional information may include information that could help RNCmanage UL CLTD information. Such information may include, for instance:the WTRU headroom (as signalled over the UPH field in the SI), WTRUvelocity (as estimated by the Node-B), etc.

In another example, the loss of PCI quality is indicated to the networkby the WTRU. Once the RNC receives the RRC message indicating that theWTRU is receiving the PCI with inferior quality, it may further indicateto the serving Node-B that the WTRU is receiving the PCI with inferiorquality and may take the appropriate action (e.g. disable UL CLTD,change serving Node-B, etc.). The Node-B may also take further actionsfor instance by changing the UL CLTD configuration via HS-SCCH orderand/or increasing the PCI transmitted power.

The following examples relate to network actions in response to PCIquality resuming to acceptable level at WTRU. In a first example, theNode-B detects the PCI quality resuming to acceptable levels viaindication by the WTRU. In this situation, the Node-B is directly awareof the PCI quality status at the WTRU and may reconfigure the WTRUappropriately. For instance, the serving Node-B may activate back ULCLTD operations.

The serving Node-B may also inform the RNC of the change in situationfor example via a new Iub signal. This signal may contain, in additionto the PCI quality status, additional information to help RNC makeappropriate configuration decisions. Such additional information mayinclude, for instance: the WTRU headroom (as signalled over the UPHfield in the SI), WTRU velocity (as estimated by the Node-B), etc.

In another example, the PCI quality resumes to acceptable levels asindicated by the WTRU to RNC. When the RNC is made aware via RRCsignalling from the WTRU that the quality of the PCI has resumed tonormal levels, it may indicate the change of status to the servingNode-B (e.g., via Iub signalling). The Node-B may then take furtheractions, for instance it may reconfigure the WTRU with an HS-SCCH orderto resume UL CLTD operations.

In further embodiments, methods may include using uplinks in a closedloop transmit diversity while operating with an enhanced dedicatedchannel (E-DCH) or a dedicated channel (DCH) in a cell forward accesschannel (CELL_FACH) state and idle mode operations. These methods maycomprise: requesting access to network resources; determining networkcapability for supporting transmit diversity; and determining based onthe network capability whether to apply transmit diversity. The methodmay include using a random access channel (RACH) to request access tonetwork resources, or to support the E-DCH. The WTRU may configure theuplink transmit diversity based on a network configuration of a randomaccess channel (RACH) partitioning.

The WTRU may also indicate in a radio resource controller (RRC) signalwhether or not it supports uplink (UL) CLTD transmission in CELL_FACHstate. The network may also signal via an information element (IE) itsuplink (UL) CLTD capabilities. And alternatively, the WTRU may read thesystem information block (SIB) to determine if a cell supports uplink(UL) CLTD in CELL_FACH, CELL_DCH mode, or idle mode.

The WTRU may use a combination of criteria to determine whether to useuplink (UL) CLTD in CELL_FACH state. The WTRU may use an E-DCH radionetwork temporary identifier (E-RNTI) to determine whether to use uplink(UL) CLTD in CELL_FACH state, or a high speed downlink shared channel(HS-DSCH) radio network transaction identifier (H-RNTI), or a cell radionetwork temporary identifier (C-RNTI) to determine whether to use uplink(UL) CLTD in CELL_FACH state. In some embodiments, the WTRU does not usea uplink (UL) CLTD to transmit a CELL UPDATE to a network.

The method may provide one or more information elements that indicatewhether the WTRU uses uplink (UL) CLTD. The resource index is providedto the WTRU. The WTRU may receive information regarding a PrecodingControl Indication Channel (PCICH). The WTRU may also receive anindication from a Node-B that indicates operation in uplink (UL) CLTDmode. The WTRU may also receive an indication to use uplink (UL) CLTDafter a collision resolution completes.

The methods may also include the WTRU selecting a transmission mode inwhich the WTRU applies an open loop transmit diversity by pre-coding adedicated physical control channel, an enhanced dedicated channel, or ahigh-speed dedicated physical control channel, with a first pre-codingweight, and transmitting a secondary pilot control channel or asecondary dedicated physical control channel with a second pre-codedweight. The WTRU may then monitor a downlink pre-coded controlinformation (PCI) but does not apply the weights that are signaled.

The WTRU may operate with space-time transmit diversity. The WTRU maythen select another transmission mode in which the WTRU applies a fullclosed loop transmit diversity by pre-coding a dedicated physicalcontrol channel, an enhanced dedicated channel, or a high-speeddedicated physical control channel, with a first pre-coding weight; andthe WTRU monitors the downlink PCI and applies the weights that aresignaled. The WTRU may use a predefined pre-coding vector until a firstPCI is received, or until a first PCI deemed to be reliable, or ofsufficient quality is received.

Thus, the WTRU may use open loop transmit diversity (OLTD) upon startingtransmission. Conversion to CLTD may be based on a trigger such as acollision resolution trigger. The WTRU may use a predetermined precoderweight on a condition that a precoding control indicator channel (PCICH)of inferior quality is detected. The WTRU may switch to the signaledprecoder weights when the signal quality of the indicator channel issufficient. Furthermore, in response to subsequently detecting inferiorPCI quality, the WTRU may continue to use previously signaled pre-codingweights for a predefined time period. The time period may be determinedusing a timer triggered by the detected inferior PCI quality, or maysimply be until reliable PCI data is received. That is, in response tothe detection of inferior PCI quality, the WTRU performing at least oneof: holding the pre-coding weights; using the pre-coding weight vectorindicated by a recent PCI with acceptable quality; stopping the closedloop transmit diversity transmission mode; or reverting to non-transmitdiversity mode.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media includecomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

Moreover, in the embodiments described above, processing platforms,computing systems, controllers, and other devices containing processorsare noted. These devices may contain at least one Central ProcessingUnit (“CPU”) and memory. In accordance with the practices of personsskilled in the art of computer programming, reference to acts andsymbolic representations of operations or instructions may be performedby the various CPUs and memories. Such acts and operations orinstructions may be referred to as being “executed,” “computer executed”or “CPU executed.”

One of ordinary skill in the art will appreciate that the acts andsymbolically represented operations or instructions include themanipulation of electrical signals by the CPU. An electrical systemrepresents data bits that can cause a resulting transformation orreduction of the electrical signals and the maintenance of data bits atmemory locations in a memory system to thereby reconfigure or otherwisealter the CPU's operation, as well as other processing of signals. Thememory locations where data bits are maintained are physical locationsthat have particular electrical, magnetic, optical, or organicproperties corresponding to or representative of the data bits. Itshould be understood that the exemplary embodiments are not limited tothe above-mentioned platforms or CPUs and that other platforms and CPUsmay support the described methods.

The data bits may also be maintained on a computer readable mediumincluding magnetic disks, optical disks, and any other volatile (e.g.,Random Access Memory (“RAM”)) or non-volatile (e.g., Read-Only Memory(“ROM”)) mass storage system readable by the CPU. The computer readablemedium may include cooperating or interconnected computer readablemedium, which exist exclusively on the processing system or aredistributed among multiple interconnected processing systems that may belocal or remote to the processing system. It should be understood thatthe embodiments are not limited to the above-mentioned memories and thatother platforms and memories may support the described methods.

No element, act, or instruction used in the description of the presentapplication should be construed as critical or essential to theinvention unless explicitly described as such. Also, as used herein,each of the articles “a” and “an” are intended to include one or moreitems. Where only one item is intended, the terms “a single” or similarlanguage is used. Further, the terms “any of” followed by a listing of aplurality of items and/or a plurality of categories of items, as usedherein, are intended to include “any of,” “any combination of,” “anymultiple of,” and/or “any combination of” multiples of the items and/orthe categories of items, individually or in conjunction with other itemsand/or other categories of items. Further, as used herein, the term“set” is intended to include any number of items, including zero.Further, as used herein, the term “number” is intended to include anynumber, including zero.

Moreover, the claims should not be read as limited to the describedorder or elements unless stated to that effect. In addition, use of theterm “means” in any claim is intended to invoke 35 U.S.C. §112, ¶ 6, andany claim without the word “means” is not so intended.

What is claimed is:
 1. A method of operating a Wireless Transmit ReceiveUnit (WTRU) in a transmit diversity mode, the method comprising: uponentering a transmit diversity mode, transmitting a signal having atleast first and second streams using default precoder weights; receivingprecoder control information on a precoder control information channel;determining a quality of the precoder control information; responsive todetermining that the quality of the precoder control information isabove a threshold, transmitting the dual-stream signal using secondprecoder weights determined based on the precoder control information.2. The method of claim 1 wherein the default precoder weights areweights that are not based on current channel conditions for thetransmitted first and second streams.
 3. The method of claim 1 whereinthe determining the second precoder weights comprises selecting thesecond precoder weights from a precoder codebook based on the precodercontrol information, the precoder codebook comprising a plurality ofsets of precoder weights.
 4. The method of claim 1 wherein the defaultprecoder weights comprise one of the plurality of sets of precoderweights comprising the precoder codebook.
 5. The method of claim 1further comprising receiving a parameter indicating resource informationof the precoder control information channel.
 6. The method of claim 5wherein the resource information is a channelization code and a slotformat.
 7. The method of claim 1 wherein the dual-stream signal includesa control channel in a first stream and a pilot signal channel in asecond stream.
 8. The method of claim 1 wherein the dual-stream signalincludes a control channel and a data channel in a first stream and apilot signal channel in a second stream.
 9. The method of claim 8wherein the default precoder weights and the second precoder weightseach comprise a first weight and a second weight that are applied to thefirst stream and a third weight and a fourth weight that are applied tothe second stream.
 10. The method of claim 1 wherein the determining thequality indicator of the precoder control information channel comprisesdetermining a signal-to-noise ratio on the precoder control informationchannel.
 11. The method of claim 1 wherein the determining the qualityindicator of the precoder control information channel comprisesdetermining a received signal strength on the precoder controlinformation channel.
 12. The method of claim 1 wherein the WTRU is in aCell_FACH (Forward Access Channel) mode upon the initialization of thetransmit diversity.
 13. The method of claim 1 wherein the WTRU is in aCell_DCH (Dedicated Control Channel) mode upon the initialization of thetransmit diversity.
 14. A wireless transmit-receive unit (WTRU)comprising: a receiver configured to receive precoder controlinformation on a precoder control information channel; a transmitterconfigured to transmit a dual-stream signal using precoder weights; aprecoder feedback processor configured to: upon initialization of atransmit diversity mode, configure the transmitter to transmit thedual-stream signal using a first set of precoder weights, wherein thefirst set of precoder weights are default precoder weights; determinethe precoder control information received on the precoder controlinformation channel, determine a quality of the precoder controlinformation; and, when the quality of the precoder control informationis above a threshold, configure the transmitter to transmit thedual-stream signal using a second set of precoder weights, the secondset of precoder weights being based on the precoder control information.15. The WTRU of claim 14 wherein the default precoder weights areweights that are not based on current channel conditions for thetransmitted first and second streams.
 16. The WTRU of claim 14 whereinthe precoder feedback processor is configured to determine the secondprecoder weights by selecting the second precoder weights from aprecoder codebook based on the precoder control information, theprecoder codebook comprising a plurality of sets of precoder weights.17. The WTRU of claim 14 wherein the default precoder weights compriseone of the plurality of sets of precoder weights comprising the precodercodebook.
 18. The WTRU of claim 14 wherein the receiver is configured toreceive a parameter indicating resource information of the precodercontrol information channel.
 19. The WTRU of claim 18 wherein theresource information is a channelization code and a slot format.
 20. TheWTRU of claim 14 wherein the transmitter is configured to transmit thedual-stream signal including a control channel in a first stream and apilot signal channel in a second stream.
 21. The WTRU of claim 14wherein the transmitter is configured to transmit the dual-stream signalincluding a control channel and a data channel in a first stream and apilot signal channel in a second stream.
 22. The WTRU of claim 21wherein the default precoder weights and the second precoder weightseach comprise a first weight and a second weight that are applied to thefirst stream and a third weight and a fourth weight that are applied tothe second stream.
 23. The WTRU of claim 14 wherein the precoderfeedback processor is configured to determine the quality indicator ofthe precoder control information channel by determining asignal-to-noise ratio on the precoder control information channel. 24.The WTRU of claim 14 wherein the precoder feedback processor isconfigured to determine the quality indicator of the precoder controlinformation channel by determining a received signal strength on theprecoder control information channel.
 25. The WTRU of claim 14 whereinthe WTRU is in a Cell_FACH (Forward Access Channel) mode at theinitialization of the transmit diversity.
 26. The WTRU of claim 14wherein the WTRU is in a Cell_DCH (Dedicated Control Channel) mode atthe initialization of the transmit diversity.